McqMate
| 501. |
Which type of heat exchanger is preferred for heavy heat loads? |
| A. | Double pipe |
| B. | Plate fine |
| C. | Series and parallel set of shell and tube |
| D. | None of these |
| Answer» C. Series and parallel set of shell and tube | |
| 502. |
For condensation of pure vapors, if the heat transfer co-efficients in filmwise and drop-wise condensation are respectively hf and hd, then |
| A. | hf = hd |
| B. | hf > hd |
| C. | hf < hd |
| D. | hf could be greater or smaller than hd |
| Answer» C. hf < hd | |
| 503. |
The unit of heat transfer co-efficient in SI unit is |
| A. | J/M2°K |
| B. | W/m2°K |
| C. | W/m°K |
| D. | J/m°K |
| Answer» B. W/m2°K | |
| 504. |
Heat transfer in the laminar sub-layer in case of a liquid flowing through a pipe, is mostly by |
| A. | Eddies current |
| B. | Conduction |
| C. | Convection |
| D. | None of these |
| Answer» B. Conduction | |
| 505. |
If the baffle spacing in a shell and tube heat exchanger increases, then the Reynolds number of the shell side fluid |
| A. | Remains unchanged |
| B. | Increases |
| C. | Increases or decreases depending on number of shell passes |
| D. | Decreases |
| Answer» D. Decreases | |
| 506. |
__________ heat exchanger is the most suitable, when the temperature of shell side fluid is much higher than that of tube side. |
| A. | Single pass, fixed tube sheet |
| B. | U-tube |
| C. | Three pass, fixed tube sheet |
| D. | None of these |
| Answer» B. U-tube | |
| 507. |
Fouling factor |
| A. | Is a dimensionless quantity |
| B. | Does not provide a safety factor for design |
| C. | Accounts for additional resistances to heat flow |
| D. | None of these |
| Answer» C. Accounts for additional resistances to heat flow | |
| 508. |
Evaporation of 1kg of water from a solution in a single effect evaporator requires about __________ kg of steam. |
| A. | 0.4 - 0.6 |
| B. | 1-1.3 |
| C. | 1.8-2 |
| D. | 2 - 2.4 |
| Answer» B. 1-1.3 | |
| 509. |
As the difference between the wall temperature and bulk temperature increases, the boiling heat transfer co-efficient |
| A. | Continues to increase |
| B. | Continues to decrease |
| C. | Goes through a minimum |
| D. | Goes through a maximum |
| Answer» C. Goes through a minimum | |
| 510. |
Thermal conductivities of most of the liquids __________ with rise in temperature. |
| A. | Increases |
| B. | Decreases |
| C. | Remains unchanged |
| D. | May increase or decrease; depends on the liquid |
| Answer» B. Decreases | |
| 511. |
The equivalent diameter for pressure drop is __________ that for heat transfer. |
| A. | Smaller than |
| B. | Greater than |
| C. | Equal to |
| D. | Not related with |
| Answer» A. Smaller than | |
| 512. |
The purpose of providing a 'catchall' in the vapor line of an evaporator is to |
| A. | Create vacuum |
| B. | Regulate the vapor flow |
| C. | Vent the non-condensable gases |
| D. | Arrest the entrained liquid |
| Answer» D. Arrest the entrained liquid | |
| 513. |
Which of the following accessories is provided in the vapor line of an evaporator for removing the entrained liquid? |
| A. | Bleed point |
| B. | Vent |
| C. | Catchall |
| D. | Baffle |
| Answer» C. Catchall | |
| 514. |
Removal of __________ heat is involved in the condensation of a vapor under saturated conditions. |
| A. | Super |
| B. | Sensible |
| C. | Latent |
| D. | Both (B) & (C) |
| Answer» B. Sensible | |
| 515. |
In a heat exchanger, floating head is provided to |
| A. | Facilitate cleaning of the exchanger |
| B. | Increase the heat transfer area |
| C. | Relieve stresses caused by thermal expansion |
| D. | Increase log mean temperature gradient |
| Answer» C. Relieve stresses caused by thermal expansion | |
| 516. |
The energy radiated from a surface Q at absolute temperature T is related as |
| A. | Q ∝ T2 |
| B. | Q ∝ T4 |
| C. | Q ∝ T3 |
| D. | None of these |
| Answer» B. Q ∝ T4 | |
| 517. |
Electromagnetic radiations propagate in vacuum with a velocity of __________ metre/second. |
| A. | 3 × 105 |
| B. | 3 × 108 |
| C. | 3 × 1010 |
| D. | 3 × 1012 |
| Answer» B. 3 × 108 | |
| 518. |
Absorptivity of a perfect black body is unity. Which of the following has maximum absorptivity? |
| A. | Aluminium foil |
| B. | Refractory bricks |
| C. | Iron plate |
| D. | Coke breeze |
| Answer» D. Coke breeze | |
| 519. |
With the increase of temperature, the Col-burn jH factor |
| A. | Increases |
| B. | Decreases |
| C. | Remains unchanged |
| D. | May increase or decrease; depending on temperature |
| Answer» A. Increases | |
| 520. |
Crystallisation of solids from a homogeneous solution is a/an __________ process. |
| A. | Exothermic |
| B. | Mildly endothermic |
| C. | Highly endothermic |
| D. | None of these |
| Answer» A. Exothermic | |
| 521. |
Pick out the wrong statement. |
| A. | Heat transfer by radiation cannot occur across an absolute volume |
| B. | In case of a shell and tube heat exchanger, the pressure drop through the shell is proportional to the number of times the fluid crosses the bundle between baffles |
| C. | Propagation velocity for travel of heat radiation through vacuum is equal to the velocity of the light |
| D. | The amount of heat involved in the condensation or vaporisation of 1 kg of a fluid is the same |
| Answer» A. Heat transfer by radiation cannot occur across an absolute volume | |
| 522. |
Steam condensate is recovered by steam traps and recycled for use as boiler feed water, because of its low |
| A. | Hardness |
| B. | Dissolved solids content |
| C. | Suspended solids content |
| D. | All (A), (B) and (C) |
| Answer» D. All (A), (B) and (C) | |
| 523. |
In case of a multipass shell and tube heat exchanger, providing a baffle on the shell side __________ the heat transfer rate. |
| A. | Increases |
| B. | Decreases |
| C. | Does not affect |
| D. | May increase or decrease, depends on the type of baffle |
| Answer» A. Increases | |
| 524. |
__________ paint has the maximum absorption coefficient. |
| A. | Black |
| B. | Yellow |
| C. | White |
| D. | Grey |
| Answer» A. Black | |
| 525. |
The advantage of backward feed multiple effect evaporators over forward feed units is that |
| A. | Heat sensitive material can be handled |
| B. | There is no additional cost of pumping |
| C. | Most concentrated liquid is at highest temperature |
| D. | Equal heat transfer co-efficients exist in various effects |
| Answer» C. Most concentrated liquid is at highest temperature | |
| 526. |
Baffles are provided in heat exchangers to increase the |
| A. | Fouling factor |
| B. | Heat transfer area |
| C. | Heat transfer co-efficient |
| D. | Heat transfer rate |
| Answer» C. Heat transfer co-efficient | |
| 527. |
Film boiling is usually not desired in commercial equipments, because |
| A. | The heat transfer rate is low in view of the large temperature drop |
| B. | It is difficult to maintain |
| C. | It is not economic |
| D. | None of these |
| Answer» A. The heat transfer rate is low in view of the large temperature drop | |
| 528. |
Pick out the wrong statement. |
| A. | Superheated steam is preferably not used for process heating because of its low heat transfer film co-efficient |
| B. | In a shell and tube heat exchanger, the shell pressure drop is maximum for orifice baffles |
| C. | S.I. unit of fouling factor is Watt/m2 .°K |
| D. | Longitudinal fins are used in extended surface heat exchangers, when the direction of fluid flow is parallel to the axis of the tube |
| Answer» C. S.I. unit of fouling factor is Watt/m2 .°K | |
| 529. |
A dephlegmator is a |
| A. | Total condenser |
| B. | Vacuum evaporator |
| C. | Partial condenser |
| D. | Double pipe heat exchanger |
| Answer» C. Partial condenser | |
| 530. |
Prandtl and Reynold's analogies are identical for Prandtl number value of |
| A. | 0 |
| B. | 0.5 |
| C. | 1 |
| D. | 5 |
| Answer» C. 1 | |
| 531. |
Reynold's analogy states that (where, St = Stanton number f = friction factor) |
| A. | St = f/2 |
| B. | St = f/4 |
| C. | St = 4f |
| D. | St = f1/2 |
| Answer» A. St = f/2 | |
| 532. |
The rate of heat transfer through a pipe wall is given by, q = 2π k (Ti- T0)/ln (ri /r0). For cylinder of very thin wall, q can be approximated by |
| A. | q = [2π k (Ti + T0)/2]/ln (ri /r0) |
| B. | q = 2π ri k (Ti- T0)/(r0/ri) |
| C. | q = 2π k (Ti- T0)/(r0/ri) |
| D. | q = 2π k (Ti- T0)/[(r0 + ri)/2] |
| Answer» D. q = 2π k (Ti- T0)/[(r0 + ri)/2] | |
| 533. |
Heat transfer by natural convection is enhanced in system with |
| A. | High viscosity |
| B. | High co-efficient of thermal expansion |
| C. | Low temperature gradients |
| D. | Low density change with temperature |
| Answer» B. High co-efficient of thermal expansion | |
| 534. |
If a single tube pass heat exchanger is converted to two pass, then for the same flow rate, the pressure drop per unit length in tube side will |
| A. | Increase by 1.8 times |
| B. | Decrease by 22 |
| C. | Increase by 216 |
| D. | Remain unchanged |
| Answer» C. Increase by 216 | |
| 535. |
At what value of Prandtl number, the hydrodynamic and thermal boundary layers of a fluid flowing over a heated plate will be identical? |
| A. | 1 |
| B. | < 1 |
| C. | > 1 |
| D. | None of these |
| Answer» A. 1 | |
| 536. |
A measure of the extent to which viscous heating is important relative to the heat flow resulting from the impressed temperature difference is represented by the __________ number. |
| A. | Condensation |
| B. | Grashoff |
| C. | Stanton |
| D. | Brinkman |
| Answer» D. Brinkman | |
| 537. |
Heat flux through several resistances in series in analogous to the current flowing through several |
| A. | Resistances in parallel |
| B. | Capacitors in series |
| C. | Resistances in series |
| D. | None of these |
| Answer» C. Resistances in series | |
| 538. |
Heat transfer efficiency leading of energy conservation in a heat exchanger can be achieved by |
| A. | Keeping the heat transfer surface clean |
| B. | Enhancing the fluid pumping rate |
| C. | Increasing the tube length |
| D. | None of these |
| Answer» A. Keeping the heat transfer surface clean | |
| 539. |
For a counter current heat exchanger with Ti h = 80°C, T°c = 60°C, T°h = 50°C and Ti c = 30°C, and the temperature difference between the two streams being the same everywhere along Z, the direction of flow of hot fluid. The temperature profile should satisfy |
| A. | d 2T/dZ2 > 0 |
| B. | d 2T/dZ2 = 0 |
| C. | d 2T/dZ2 < 0 |
| D. | dT/dZ = 0 |
| Answer» B. d 2T/dZ2 = 0 | |
| 540. |
Which is the most suitable for the concert-ration of highly concentrated solution? |
| A. | Open pan evaporation |
| B. | Long tube vertical evaporator |
| C. | Agitated film evaporator |
| D. | None of these |
| Answer» A. Open pan evaporation | |
| 541. |
For gases, the thermal conductivity increases with temperature rise. For liquids, with increase in concentration, its thermal conductivity generally |
| A. | Decreases |
| B. | Increases |
| C. | Remains unchanged |
| D. | Increases exponentially |
| Answer» A. Decreases | |
| 542. |
A hot liquid is kept in a big room. The logarithm of the numerical value of the temperature difference between the liquid and the room is plotted against time. The plot will be very nearly a/an |
| A. | Ellipse |
| B. | Straight line |
| C. | Parabola |
| D. | Circular arc |
| Answer» B. Straight line | |
| 543. |
With increase in the distance between the heat source and the object receiving the heat, the radiation heat transfer |
| A. | Decreases |
| B. | Increases |
| C. | Increases exponentially |
| D. | Remain unaffected |
| Answer» A. Decreases | |
| 544. |
Prandtl number is the ratio of |
| A. | Mass diffusivity to thermal diffusivity |
| B. | Momentum diffusivity to thermal diffusivity |
| C. | Thermal diffusivity to mass diffusivity |
| D. | Thermal diffusivity to momentum diffusivity |
| Answer» B. Momentum diffusivity to thermal diffusivity | |
| 545. |
Double pipe heat exchangers are preferably useful, when |
| A. | High viscosity liquid is to be cooled |
| B. | Requirement of heat transfer area is low |
| C. | Overall heat transfer co-efficient is very high |
| D. | A corrosive liquid is to be heated |
| Answer» B. Requirement of heat transfer area is low | |
| 546. |
A hot body will radiate heat most rapidly, if its surface is |
| A. | White & rough |
| B. | Black & rough |
| C. | White & polished |
| D. | Black & polished |
| Answer» B. Black & rough | |
| 547. |
Rate of heat transfer by vaporisation from pools of water is affected by the |
| A. | Nature of heating surface and distribution of bubbles |
| B. | Surface tension of water |
| C. | Viscosity of water |
| D. | All (A), (B) and (C) |
| Answer» D. All (A), (B) and (C) | |
| 548. |
Thickness of thermal boundary layer is more compared to that of hydrodynamic boundary layer, when the value of Prandtl number is |
| A. | 1 |
| B. | < 1 |
| C. | > 1 |
| D. | > 5 |
| Answer» B. < 1 | |
| 549. |
The purpose of providing bleed points in the evaporator is to |
| A. | Admit the feed |
| B. | Remove the product |
| C. | Facilitate removal of non-condensable gases |
| D. | Create vacuum |
| Answer» C. Facilitate removal of non-condensable gases | |
| 550. |
Choose the most important factor on which the heat conducted through a wall in a unit time will depend on? |
| A. | Thickness of the wall |
| B. | Area of the wall perpendicular to heat flow |
| C. | Material of the wall |
| D. | Temperature difference between the two surfaces of the wall |
| Answer» D. Temperature difference between the two surfaces of the wall | |
| 551. |
With increase in temperature, the thermal conductivity of steel |
| A. | Increases |
| B. | Decreases |
| C. | Remains unchanged |
| D. | Increases exponentially |
| Answer» B. Decreases | |
| 552. |
Film boiling occurs at __________ pressure. |
| A. | Atmospheric |
| B. | Sub-atmospheric |
| C. | Negative |
| D. | Very high |
| Answer» D. Very high | |
| 553. |
In a shell and tube heat exchanger, the tube side heat transfer co-efficient just at the entrance of the tube is |
| A. | Infinity |
| B. | Zero |
| C. | Same as average heat transfer co-efficient for tube side |
| D. | None of these |
| Answer» A. Infinity | |
| 554. |
At Pr > 1, conduction in an ordinary fluid flowing through a heated pipe is limited to the |
| A. | Buffer zone |
| B. | Turbulent core |
| C. | Both (A) and (B) |
| D. | Viscous sub-layer |
| Answer» D. Viscous sub-layer | |
| 555. |
Which of the following is the most controlling factor for the rate of bubble detachment from the hot solid surface? |
| A. | Liquid density |
| B. | Liquid viscosity |
| C. | Hot surface temperature |
| D. | Interfacial tension |
| Answer» D. Interfacial tension | |
| 556. |
'Fouling factor' used in the design of a multipass shell and tube heat exchanger is a www.objectivebooks.com |
| A. | Non-dimensional factor |
| B. | Factor of safety |
| C. | Conversion factor for individual film heat transfer co-efficient to overall heat transfer coefficient |
| D. | None of these |
| Answer» B. Factor of safety | |
| 557. |
Radiation heat transfer rates does not depend upon the |
| A. | Type of absorbing surface |
| B. | Distance between the heat source and the object receiving the heat |
| C. | Surface area and temperature of the heat source |
| D. | None of these |
| Answer» D. None of these | |
| 558. |
Economy of an evaporator is influenced by the |
| A. | Steam pressure |
| B. | Feed temperature |
| C. | Number of effect |
| D. | Both (B) & (C) |
| Answer» D. Both (B) & (C) | |
| 559. |
If all the conditions and dimensions are same, then the ratio of velocity through the tubes of a double pass heat exchanger to that through the single pass heat exchanger is |
| A. | 1 |
| B. | 2 |
| C. | 1/2 |
| D. | 4 |
| Answer» B. 2 | |
| 560. |
Circulation pump is located below the evaporator to |
| A. | Avoid cavitation |
| B. | Avoid frequent priming |
| C. | Create more suction head |
| D. | None of these |
| Answer» C. Create more suction head | |
| 561. |
Which of the following is not concerned with the heat transfer? |
| A. | Brinkman number |
| B. | Stanton number |
| C. | Schmidt number |
| D. | Peclet number |
| Answer» C. Schmidt number | |
| 562. |
Which of the following has the highest thermal conductivity? |
| A. | Brick |
| B. | Air |
| C. | Water |
| D. | Silver |
| Answer» D. Silver | |
| 563. |
__________ equation relates the thermal conductivity of a solid to its temperature. |
| A. | Antoine |
| B. | Kopp's |
| C. | Lee's |
| D. | Kistyakowsky |
| Answer» C. Lee's | |
| 564. |
A hollow sphere and a solid sphere of the same material and equal radii are heated to the same temperature. In this case, |
| A. | The cooling rate will be the same for the two spheres and hence the two spheres will have equal temperatures at any instant |
| B. | Both the spheres will emit equal amount of radiation per unit time in the beginning |
| C. | Both will absorb equal amount of radiation from the surrounding in the beginning |
| D. | Both (B) & (C) |
| Answer» D. Both (B) & (C) | |
| 565. |
Unsteady state heat conduction occurs, when |
| A. | Temperature distribution is independent of time |
| B. | Temperature distribution is dependent on time |
| C. | Heat flows in one direction only |
| D. | Three dimensional heat flow is concerned |
| Answer» B. Temperature distribution is dependent on time | |
| 566. |
A __________ surface has the maximum thermal emissivity out of the following. |
| A. | Black & smooth |
| B. | Black & rough |
| C. | White & smooth |
| D. | White & rough |
| Answer» B. Black & rough | |
| 567. |
For specified tube outside diameter, higher BWG means higher |
| A. | Tube thickness |
| B. | Cross-sectional area |
| C. | Weight per unit length |
| D. | None of these |
| Answer» B. Cross-sectional area | |
| 568. |
1 BTU/hr.ft.°F is equal to __________ kcal/hr. m.°C. |
| A. | 1.49 |
| B. | 1 |
| C. | 4.88 |
| D. | None of these |
| Answer» A. 1.49 | |
| 569. |
A long iron rod initially at a temperature of 20°C has one end dipped in boiling water (100°C) at time, t = 0. The curved surface of the rod is insulated so that heat conduction is one dimensional in the axial direction. The temperature at a distance 100 mm from the dipped end becomes 40°C at time, t = 200 s. The same temperature is achieved at a distance of 200 mm from the dipped end at time |
| A. | t = 283 s |
| B. | t = 356 s |
| C. | t = 400 s |
| D. | t = 800 s |
| Answer» D. t = 800 s | |
| 570. |
Multiple effect evaporation is generally recommended, when the |
| A. | Large scale evaporation of liquor is needed |
| B. | Corrosive liquids are to be concentrated |
| C. | Fuel is cheaply available |
| D. | Evaporation on small scale is to be done |
| Answer» A. Large scale evaporation of liquor is needed | |
| 571. |
Value of Prandtl number for water ranges from |
| A. | 1 to 2 |
| B. | 5 to 10 |
| C. | 100 to 500 |
| D. | 1000 to 2000 |
| Answer» B. 5 to 10 | |
| 572. |
Which of the following is correct? |
| A. | Rate = Driving force × Resistance |
| B. | Driving force = Rate × Resistance |
| C. | Resistance = Driving force × Rate |
| D. | Rate = Resistance/Driving force |
| Answer» B. Driving force = Rate × Resistance | |
| 573. |
For a fluid flowing in an annulus space, the wetted perimeter for heat transfer and pressure drop are |
| A. | Same |
| B. | Different |
| C. | Never different |
| D. | Linearly related |
| Answer» B. Different | |
| 574. |
Steam is routed through the tube in case of a __________ evaporator. |
| A. | Basket type |
| B. | Horizontal tube |
| C. | Short tube vertical |
| D. | Long tube vertical |
| Answer» B. Horizontal tube | |
| 575. |
1000 kg of wet solids are to be dried from 60% to 20% moisture (by weight). The mass of moisture removed in kg is |
| A. | 520 |
| B. | 200 |
| C. | 400 |
| D. | 500 |
| Answer» C. 400 | |
| 576. |
The sum of reflectivity and absorptivity for an opaque body is equal to |
| A. | 0.5 |
| B. | 1 |
| C. | 0 |
| D. | 2 |
| Answer» B. 1 | |
| 577. |
Dropwise condensation occurs on __________ surfaces. |
| A. | Clean and dirt free |
| B. | Smooth clean |
| C. | Contaminated cooling |
| D. | Polished |
| Answer» C. Contaminated cooling | |
| 578. |
In a backward feed multiple effect evaporator |
| A. | Feed is introduced in the first effect |
| B. | Feed flows from low pressure to high pressure |
| C. | No pumps are required between successive effects |
| D. | None of these |
| Answer» B. Feed flows from low pressure to high pressure | |
| 579. |
Conduction occurs in the buffer zone for a fluid flowing through a heated pipe, only when Prandtl number is |
| A. | 0.1 |
| B. | > 1 |
| C. | < 1 |
| D. | 1 |
| Answer» A. 0.1 | |
| 580. |
For a given ambient air temperature with increase in the thickness of insulation of a hot cylindrical pipe, the rate of heat loss from the surface would |
| A. | Decrease |
| B. | Increase |
| C. | First decrease and then increase |
| D. | First increase and then decrease |
| Answer» D. First increase and then decrease | |
| 581. |
In thermal radiation for a black body (where, ε is emissivity and α is absorptivity) |
| A. | α = 1; ε ≠ 1 |
| B. | α ≠ 1, ε = 1 |
| C. | α ≠ 1, ε ≠ 1 |
| D. | α = 1; ε = 1 |
| Answer» D. α = 1; ε = 1 | |
| 582. |
The type of liquor circulation system to be ' employed in evaporators (viz. natural or forced circulation) is determined mainly by the __________ of the liquid. |
| A. | Viscosity |
| B. | Density |
| C. | Thermal conductivity |
| D. | Corrosive nature |
| Answer» A. Viscosity | |
| 583. |
Nusselt number (for forced convection heat transfer) is a function of the __________ number. |
| A. | Prandtl |
| B. | Reynolds |
| C. | Both (A) & (B) |
| D. | Neither (A) nor (B) |
| Answer» C. Both (A) & (B) | |
| 584. |
In case of __________ boiling, the bubbles formed on a submerged hot surface get absorbed in the mass of the liquid. |
| A. | Nucleate |
| B. | Pool |
| C. | Low pressure |
| D. | None of these |
| Answer» B. Pool | |
| 585. |
The separation of liquid droplets from the vapor is done by a/an __________, in the evaporators. |
| A. | Steam ejector |
| B. | Entrainment separator |
| C. | Compressor |
| D. | Vacuum pump |
| Answer» B. Entrainment separator | |
| 586. |
For the same heat transfer area and the terminal conditions, the ratio of the capacities of a single effect evaporator to a triple effect evaporator is |
| A. | 3 |
| B. | 0.33 |
| C. | 1 |
| D. | 1.33 |
| Answer» C. 1 | |
| 587. |
A dilute aqueous solution is to be concentrated in an evaporator system. High pressure steam is available. Multiple effect evaporator system is employed, because |
| A. | Total heat transfer area of all the effects is -less than that in a single effect evaporator system |
| B. | Total amount of vapor produced per Kg of feed steam in a multiple effect system is much higher than in a single effect |
| C. | Boiling point elevation in a single effect system is much higher than that in any effect in a multi-effect system |
| D. | Heat transfer co-efficient in a single effect is much lower than that in any effect in a multieffect system |
| Answer» B. Total amount of vapor produced per Kg of feed steam in a multiple effect system is much higher than in a single effect | |
| 588. |
In a boiling curve, the peak heat flux is called the __________ point. |
| A. | Nusselt |
| B. | Leidenfrost |
| C. | Boiling |
| D. | Burnout |
| Answer» D. Burnout | |
| 589. |
Film condensation is promoted on a/an __________ surface. |
| A. | Oily |
| B. | Coated |
| C. | Clean & smooth |
| D. | Dirty |
| Answer» C. Clean & smooth | |
| 590. |
The equivalent diameter for the annulus of a double pipe heat exchanger, whose inner pipe has fins on the outside is __________ compared to the same size pipes without fins. |
| A. | More |
| B. | Less |
| C. | Same |
| D. | Unpredictable |
| Answer» B. Less | |
| 591. |
The wavelength at which the maximum monochromatic emissive power occurs for a black body, is (where, T = absolute temperature of the black body). |
| A. | αT |
| B. | α × 1/T |
| C. | α T4 |
| D. | Independent of T |
| Answer» B. α × 1/T | |
| 592. |
In a 1-1 concurrent heat exchanger, if the tube side fluid outlet temperature is equal to the shell side fluid outlet temperature, then the LMTD is |
| A. | ∞ |
| B. | 0 |
| C. | Equal to the difference between hot and cold fluids inlet temperature |
| D. | Equal to the difference between hot fluid inlet temperature and cold fluid outlet temperature |
| Answer» B. 0 | |
| 593. |
According to Reynolds analogy, Stanton number is equal to (where, f = Fanning friction factor) |
| A. | 2f |
| B. | f |
| C. | f/2 |
| D. | f/4 |
| Answer» C. f/2 | |
| 594. |
Grashoff number, which is defined as g . β (Ts - T∞) ρ2. L3/μ2, is proportional to the ratio of buoyancy force to __________ force. |
| A. | Viscous |
| B. | Elastic |
| C. | Inertial |
| D. | None of these |
| Answer» A. Viscous | |
| 595. |
In forced circulation, the heating element is injected |
| A. | Internally |
| B. | Externally |
| C. | Both (A) and (A) |
| D. | Neither (A) nor (B) |
| Answer» A. Internally | |
| 596. |
If the thermal conductivity of a wall material is independent of temperature, the steady state temperature distribution in the very large thin plane wall having steady, uniform surface temperature follows __________ law. |
| A. | Hyperbolic |
| B. | Parabolic |
| C. | Linear |
| D. | Logarithmic |
| Answer» C. Linear | |
| 597. |
Pick out the wrong statement. |
| A. | The condensing film co-efficient is about 3 times lower for vertical condenser as compared to the equivalent horizontal condenser for identical situation |
| B. | Film co-efficient for vaporisation decreases as a result of vapor binding |
| C. | In industrial practice, sub-cooling of condensate is required, when the condensate is a volatile liquid and is to be transferred for storage |
| D. | Overall heat transfer co-efficient in a heat exchanger is controlled by the value of the film coefficient, which is higher |
| Answer» D. Overall heat transfer co-efficient in a heat exchanger is controlled by the value of the film coefficient, which is higher | |
| 598. |
Viscous & heat sensitive liquids are concentrated in __________ evaporators. |
| A. | Open pan |
| B. | Long tube |
| C. | Agitated film |
| D. | None of these |
| Answer» C. Agitated film | |
| 599. |
When does the heat generated by fluid friction becomes appreciable compared to the heat transferred between the fluids? |
| A. | At high fluid velocity |
| B. | At low velocity |
| C. | When fluid flows past a smooth surface |
| D. | None of these |
| Answer» A. At high fluid velocity | |
| 600. |
During crystallisation, formation of crystal can occur in __________ solution only. |
| A. | Saturated |
| B. | Supersaturated |
| C. | Under-saturated |
| D. | All (A), (B) and (C) |
| Answer» B. Supersaturated | |
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